1. Field of the Invention
This invention is directed to solid electrolytes containing a polymer matrix and an electrolyte solvent (plasticizer) for the polymer matrix. This invention is further directed to a photoelectrochemical cell employing the polymer matrix.
1. State of the Art
Photoelectrochemical cells are photovoltaic devices based on the junction of a semiconductor photoelectrode and an electrolyte containing a redox couple, such as I.sup.- /I.sub.3.sup.- /I.sub.2 or S.sup.2- /S.sup.2- /S.sub.x+1.sup.2-. These systems have heretofore generally employed n-type semiconductors and transparent electrodes. Illumination produces photogenerated holes that oxidize the complex anions in the electrolyte solution, while electrons travel from the semiconductor through an external load to reduce the species at the transparent illuminated surface. Rediffusion in the electrolyte of the species completes the electrochemical cycle.
Polymeric electrolytes such as polyethylene oxide (PEO) have been used in photoelectrochemical cells to eliminate corrosion and side reactions of the semiconductor/electrolyte interface which are commonly observed with conventional electrolyte solvents.
However, cells with PEO electrolytes have relatively low conductivity and hence low efficiency. See Gray, "Solid Polymer Electrolytes; Fundamentals and Technological Applications," VCH Publishers, 1991, pp 28-29.
There is thus a need in the art for an electrolyte for a photoelectrochemical cell having increased conductivity but retaining the resistance to corrosion and side reactions of PEO.